Hip Joint Anatomy PDF

HIP JOINT BY GM MUWANGA Hip Joint hip joint is a spheroidal type of synovial joint formed between the head of femur and the acetabulum of the hip bone a typical “ball-and-socket ” joint Articular surfaces head of the femur is globular and forms two-thirds of...

HIP JOINT BY GM MUWANGA Hip Joint hip joint is a spheroidal type of synovial joint formed between the head of femur and the acetabulum of the hip bone a typical “ball-and-socket ” joint Articular surfaces head of the femur is globular and forms two-thirds of a sphere covered by an articular cartilage which is thickest superiorly in the line of weight bearing Articular surfaces (contn.) cartilage thins out inferiorly cartilage is also missing at the pit or fovea where the ligament of the head of femur attaches Proximal part of femur. Note articular surface (gray) on the head of Right femur - proximal view. For clarity, the acetabulum has been sectioned in the horizontal plane. The distal end of the femur (with patella) has been added in light shading. Articular surfaces (contn.) articular (lunate ) surface of the acetabulum is horse-shoe-shaped cartilage is thick superiorly, but thins out inferiorly A metallic horseshoe Articular surfaces (contn.) articular surface forms an arch around the non-articularacetabular fossa latter contains a mass of fat covered by the synovial membrane Articular surfaces (contn.) rim of the acetabulum bears the acetabular notch inferiorly latter is bridged-over by thetransverse acetabular ligament acetabulum is thickened by a fibrocartilage known as theacetabular labrum Acetabular labrum: is attached to the:  bony rim of the acetabulum  transverse acetabular ligament Acetabulum of right hip – lateral view. Note lunate surface covered by articular cartilage. Left acetabulum. Note lunate surface, acetabular fossa & transverse acetabular ligament. Acetabular labrum (contn.): free thin edge of the labrum cups around the head of femur & holds it firmly helps to prevent dislocation Articular capsule quite strong and thick consists of both a synovial and a fibrous component proximally, the fibrous capsule attaches to:  edge of the acetabulum Hip joint – anterior view. Note attachment of fibrous capsule around the edge of acetabulum. Left hip joint with Articular capsule opened. Note cut synovial membrane & the articular surfaces. Articular capsule (contn.) distally, the capsule attaches anteriorly to the intertrochanteric line posteriorly, it covers only two-thirds of the neck of the femur Right hip joint anterior view. Note proximal & distal attachments of the fibrous joint capsule. Right hip joint posterior view. Note proximal & distal attachments of the fibrous joint capsule. Articular capsule (contn.) most capsule fibres are longitudinal, running from the pelvis to the femur however, some deeper fibres run circularly around the neck of the femur these fibres form theorbicular zone which helps to hold the head of the femur in the acetabulum Hip joint – fibrous capsule Note orbicular zone Articular capsule (contn.) articular capsule is further strengthened by the presence of the3 intrinsic igaments latter are thickened parts of the fibrous capsule are named after the part of the hip bone Intrinsic ligaments ligaments are:  iliofemoral ligament  pubofemoral ligament  ischiofemoral ligament Ligaments of the right hip joint – lateral view.  Ligaments (contn.) another ligament runs within the joint cavity :  is called theligament of the head of femur (ligamentum capitis femoris ) (A) Intrinsic ligaments (i) iliofemoral ligament: (Y ligament of Bigelow) lies on the anterior surface of the capsule has aninverted Y shape , the stem being attached to the anterior inferior iliac spine iliofemoral ligament (contn) diverging fibres attach to the entire length of the intertrochanteric line iliofemoral ligamentbecomes tense in full extension of the hip joint hence helps to maintain the erect posture Hip joint – anterior view. Note iliofemoral ligament.  Iliofemoral ligament ** – anterior view * *  Iliofemoral ligament ** – anterior view ** iliofemoral ligament (contn.) contributes to the “screw-home ” effect occurs as the hip becomes fully extended, so that capsule is twisted and shortened results in the head of the femur being guided like a screw into its socket (i.e., the acetabulum) Right hip joint in extension, lateral view. The capsular ligaments of the hip form a ring-like collar that encircles the femoral neck. When the hip is extended, these ligaments become twisted upon themselves, pushing the femoral head more firmly into the acetabulum (“screw-home” effect) Right hip joint in flexion, lateral view. During flexion), the ligament fibers are lax and press the femoral head less firmly into the acetabulum, allowing a greater degree of femoral mobility. iliofemoral ligament (contn.) iliofemoral ligament is also important n the mechanism called “locking of the hip joint” in this mechanism, the individual is able to stand upright with little expenditure of energy in form of muscle contraction iliofemoral ligament (contn.) thus in full extension of the hip joint, the head of femur & acetabulum now almost fit tightly together iliofemoral ligament becomes taut (tense), thus preventing hyper-extension hence body weight is now supported (ii) pubofemoral ligament is applied to themedial &inferior parts of the capsule becomes tight during extension of the hip joint also limits abduction Hip joint – posterior view. Note iliofemoral & ischiofemoral ligaments. (iii) ischiofemoral ligament lies on theposterior aspect of the joint capsule arises from theischial portion of the acetabulum thenspirals laterally andsuperiorly across the posterior part of the femoral neck Hip joint – posterior view: note ischiofemoral ligament (B) Ligament of the head of femur is intracapsular , being surrounded by a synovial membrane artery of head of femur travels within ligament of head of femur Ligament of the head of femur – note artery of head of femur within substance of the ligament Note that artery of head of femur is a branch of the obturator Acetabulum of hip joint. Note: The ligament of the femoral head (cut) transmits branches from the obturator artery that nourish the femoral head. Ligament of the head of femur (contn.) arises from the margins of the acetabular notch &transverse acetabular ligament ends in the fovea of the head of femur  Ligament of the head of femur (contn). is about 3.5 cm long appears to be of little importance as regards prevention of hip joint dislocation however, it becomes stretched when the femur is abducted Hip joint – coronal section: note disposition of ligament of head of femur ** within joint cavity. ** Joint capsule: capsule has been divided and the femoral head dislocated to expose the cut ligament of the head of the femur. Blood supply to neck & head of femur branches of lateral circumflex femoral artery branches of medial circumflex femoral artery all the above are branches of profunda femoris artery Arteries of the hip joint – anterior viewin situ. Note deep artery of thigh (profundal femoris artery). Blood supply to neck & head of femur (contn.) ligament of the head of femur usually contains theartery of the head of femur artery of the head of femur is a branch of the obturator artery Blood supply of head & neck of femur: - Branches of the medial & lateral circumflex femoral arteries (branches of the profunda femoris artery), & artery to the femoral head (a branch of the obturator artery) supply the head & neck of the femur. In the adult, the medial circumflex femoral artery is the most important source of blood to the femoral head & adjacent (proximal) neck. Arteries of the Hip joint.  Fractures of the femoral neck often disrupt the blood supply to the head of the femur. The medial circumflex femoral artery supplies most of the blood to the head and neck of the femur. This artery is often torn when the femoral neck is fractured. In such cases, the artery to the ligament of the femoral head may be the only remaining source of blood to theproximal ragment of the femoral head. This blood supplyoften is inadequate. Consequently, the proximal fragment will receive little or no blood aseptic avascular necrosis and may undergo sue( death ). Right femur, coronal section. Fracture of neck of femur: the Garden classification identifies four fracture types: I: impaction of superior portion of femoral neck (incomplete fracture) II: nondisplaced fracture (complete fracture) III: partial displacement between femoral head & neck IV: complete displacement between femoral Type I. Impacted fracture Type II. Nondisplaced fracture. Type III. Partially displaced Type IV. Displaced fracture. The synovial membrane lines the fibrous capsule & lines the ligament of the head of femur also surrounds the fat pad of the acetabular fossa & covers the acetabular labrum Synovial membrane: extends laterally from the acetabular rim is reflected onto the femoral neck within the joint cavity continues up the femoral neck to the chondro-osseous junction of the femoral head Hip joint – anterior view. Fibrous joint capsule has been removed at level of femoral neck to show extent synovial membrane. Hip joint – posterior view. Fibrous joint capsule has been removed at level of femoral neck to show extent synovial membrane.  The synovial membrane (contn.) there is a prolongation of the synovial capsule beyond the free inferior margin of the fibrous capsule posteriorly prolongation serves as the bursa for the tendon of theobturator externus muscle Note prolongation of synovial membrane beyond orbicular zone Movements of the hip joint hip joint capable of a wide range of movements (i) extension and flexion (ii) abduction and adduction (iii) medial and lateral rotation (iv) circumduction Medial & lateral rotators of hip Joint. Lateral rotators of hip joint. Blood supply of the hip joint Arteries of the hip joint are branches of the: medial and lateral circumflex femoral arteries inferior gluteal artery deep division of the superior gluteal artery Nerve supply to the hip joint joint has four sources of nerve supply : (a) femoral nerve (b) sciatic nerve (c) anterior division of the obturator nerve (d) superior gluteal nerve Factors helping to maintain joint stability hip joint is very stable femoral head is closely fitted to the acetabulum Factors helping to maintain joint stability (contn.) area of acetabulum covering head exceeds half a sphere acetabular labrum deepens this area further & helps to restrain femoral head in the socket Factors helping to maintain joint stability (contn.) joint capsule is thick is reinforced by the three major ligaments:  iliofemoral ligament  pubofemoral ligament  ischiofemoral ligament Some clinical aspects of the hip joint (i) Dislocation of the hip joint nature of the articular surfaces of the hip joint & surrounding ligaments confer a high degree of stability to this joint therefore,dislocation is rare , except when extreme forces are involved Some clinical aspects of the hip joint (contn.) such forces are encountered in car accidents in these situations:  the individual is in a sitting position  hence thehip joint is flexed & the femur medially rotated Some clinical aspects of the hip joint (contn.) in a car collision, there may be a forceful impact of the knee with the dashboard force is transmitted through the femur into the hip joint, thus causing dislocation Some clinical aspects of the hip joint (contn.) when this happens, thefemoral head s dislodged from the acetabulum head also displaced superiorly along the lateral surface of the ilium affected limb is shortened &medially Traumatic dislocation of the hip – the thigh assumes a position of adduction and slight internal rotation.  (ii) Traumatic fracture of the neck of femur neck of the femur is prone to fracture in individuals who areover sixty years of age is mainly due to a condition called osteoporosis (rarefaction, bone becoming more porous ) latter weakens the femoral neck with  Traumatic fracture of the neck of femur (contn.) condition more common in women in whichosteoporosis is relatively more severe than in men osteoporosis due to hormonal mbalance that follows menopause in women  Traumatic fracture of the neck of femur (contn.) under these circumstances, usually a small force is enough to cause the fracture of the femoral neck such force could be duefalling after slipping ortripping on an object  Traumatic fracture of the neck of femur (contn.) fracture of the neck of femur also interferes with blood supply to the femoral head latter undergoes ischemic necrosis, also known as avascular necrosis of the head of femur  (iii) Osteoarthritis (degenerative arthritis) a painful condition of the hip in which the articular cartilage gets progressively destroyed results in bits of thearticular cartilage disappearing , so that thearticular surfaces are no longer smooth  Hip with arthritis Normal hip Hip joint - osteoarthritis